Texture/TextureIO: Make 'wrapping' Texture ctor public, remove same factory method from TextureIO
Minor edits: Fix comments / API-docs
Bug 801: Split GraphUI's TextureButton: TextureSeqButton (Base) and it's derivations ImageSeqButton + GLEventListenerButton + MediaPlayerButton

Split GraphUI's TextureButton to TextureSeqButton (Base) and it's derivations:
 - ImageSeqButton
   - displays an ImageSequence

 - GLEventListenerButton
   - displays any GLEventListener as rendered into FBO as an ImageSequence

 - MediaPlayerButton
   - displays movies

- Added public ImageSequence impl. TextureSequence,
  was private SingleTextureSeqFrame.

- Demo GPUUISceneGLListener0A shows:
  - MediaPlayerButton w/ Big Buck Bunny film
  - GLEventListenerButton w/ GearsES2
  - ImageSeqButton w/ 2 textures (pressed/released)
Bug 801: Fix RegionRenderer's TextureSequence shader program selection (recognize diff. TextureLookupFragmentShader and TextureSampler2DType)

Fix RegionRenderer's TextureSequence shader program selection,
i.e. TextureLookupFragmentShader and TextureSampler2DType are considered in the ShaderProgram hash key selector.

Now the proper ShaderProgram for different TextureSequence objects will be selected,
e.g. diff video pixel formats and/or texture sampler types.
Extract FFMPEGNatives's Audio + Video formats to their own class in AV private package.

jogamp.opengl.util.av.impl.FFMPEGNatives.SampleFormat -> jogamp.opengl.util.av.AudioSampleFormat
jogamp.opengl.util.av.impl.FFMPEGNatives.PixelFormat -> jogamp.opengl.util.av.VideoPixelFormat

.. to be reused for other decoders later-on.